Rheem Professional Classic Gas Water Heater, Inlet Connection Size: 3/4 in, Outlet Connection Size: 3/4 in, BTU Rating: 4000 Btu/hr, Gas Type: Natural Gas, Tank Capacity: 50 gal, Energy Efficiency: 0.63, Recovery Rate: 40.4 gph, Vent Size: 3, 4 in, Gas Connection Height: 14-1/4 in, Tank Height: 51-1/8 in, Emissions: Low, Dimensions: 23-3/4 in Dia x 54-1/4 in H, Includes: Temperature and Pressure Relief Valve